Abstract: The invention is directed to a circuit for conditioning the output signal of a measuring sensor for further processing in a control apparatus which has a fixed ground potential which does not necessarily correspond to the ground potential of the measuring sensor. A conditioning circuit is provided which can be integrated on a chip and has the following characteristics. The conditioning circuit compensates for the fluctuating ground offset between exhaust gas probe and control apparatus ground when utilizing an exhaust gas probe burdened with a potential. The circuit arrangement includes an external circuit which can be changed to influence the input signal to the conditioning circuit. With this changeable external circuit, the output signal of the circuit arrangement can be so modified that the control apparatus outputs an output voltage with offset and an output voltage without offset.

Abstract: The monitoring circuit for a sensor connected to a low-potential and high-potential line, such as a thermal element, includes a high-resistance pulldown resistor connected between the high potential line and ground, a offset voltage source connected to the low-potential line to supply an offset voltage higher than a minimum transistor control voltage; first and second testing transistor shaving control electrodes connected to respective ones of the lines via resistor arrangements; and a third testing transistor having a control electrode connected to an output of a p-type channel FET having a control electrode connected to one of the two sensor lines. Whether the operating state of the sensor is normal, involves a short circuit to ground or the supply voltage or an interruption of the sensor lines is determined by monitoring the switching states of the first testing transistor and a series combination of the second and third testing transistor.

Abstract: A system for monitoring the operability of a probe heating device is introduced which comprises a probe heater, an arrangement which supplies the probe heater with the necessary electrical energy and the corresponding supply leads. The essence of the invention is that the heating current for a probe heater causes a measuring voltage on a measuring resistor connected in series with the probe heater. The measuring voltage is compared to a further voltage which is emitted by a reference element. The reference element is at a similar temperature as the measuring resistor or receives a measuring signal which corresponds to the temperature of the measuring resistor and emits a voltage which has a similar temperature response as the measuring voltage. By means of this comparison of both voltages, it is possible to conclude as to the current flowing through the heater and therefore as to the operability of the probe heating device without switching too high a resistor in series with the probe heater.

Abstract: An apparatus for resetting computing devices, particularly devices for fuel proportioning or fuel injection, for adjusting ignition timing, and the like, which are controlled by microprocessors, includes a resetting circuit to evaluate the change in the switching state of the ignition lock switch of the motor vehicle when restarted. The evaluation is effected independently of the supply voltage still at the computing device due to a self-sustaining circuit, by means of an integrated differentiation and the differentiation voltage is fed to a comparator at whose output the reset pulse is formed.